TORTOISE & HARE

class Node: #node creation
    def __init__(self,data):
        self.data=data
        self.next=None
class Llist: #main logic for list
    def __init__(self):
        self.head=None
    def build(self,data):
        new_node=Node(data) #calling Node class for creation of new_node
        if self.head is None:
            self.head=new_node
        else:
            temp=self.head
            while temp.next is not None:
                temp=temp.next
            temp.next=new_node
    #TORTOISE & HARE APPROACH
    def find_middle(self):
        slow=self.head
        fast=self.head
        #Traverse the list with two pointers
        while fast is not None and fast.next is not None:
            slow=slow.next
            fast=fast.next
        return slow
    def display(self):
        temp=self.head
        while temp is not None:
            print(temp.data,end="->")
            temp=temp.next
        print("None")
l1=Llist()
l1.build(1)
l1.build(2)
l1.build(4)
l1.build(5)
print("List 1:")
l1.display()
middle_node=l1.find_middle()
print("Middle Node:",middle_node.data if middle_node else "List is empty")